Project summary: This proposal will utilize a novel visual fixation task to determine if differences in behavioral reactivity at four months are related to individual differences in the development of visual attention. Four-month-old infants will be brought into the lab and rated on their level of behavioral reactivity to novel visual and auditory events. After a short break, these infants will then be shown a series of visual stimuli designed to manipulate the level of response conflict by varying the congruence of the cue and the target. For each trial, infants will be presented with a fixation stimulus followed by a cue, (visual/spatial, auditory/non-spatial, both, or neither) a brief delay, and then a target presented either contralaterally or ipsilaterally to the cue. Latency to orient and direction of orientation will be recorded for each trial type, and results will be analyzed as a function of trial type and behavioral reactivity score. These infants will subsequently be retested in the same Infant Orienting Task (IOT) at 6, 9, and 12 months. It is hypothesized that performance on the IOT will vary both as a function of age, and as a function of behavioral reactivity at four months. Moreover, data collected from this longitudinal sample will provide a rich source of information regarding the development of attentional competence, and for the first time, will allow us to use the same task to measure the development of individual components of attention in both 4-month-old infants, and 18- month-old infants. Relevance: This work has the potential to significantly impact our understanding of the origins of individual differences in attentional style. By exploring the link between early behavior and later attentional development, these studies will contribute significantly to our understanding of how attention develops in non-clinical populations, and potentially, if the appearance of attentional dysfunction is preceded by systematic differences in the development of the components of attention.